Although Germany entered the Second World War with a better technique in arms and more readily and well-trained soldiers, during the war, the Allies gained an advantage. The spirit of patriotism and national freedom, by the peoples of the Allies, and by the smaller nations that participated in the war, were certainly contributed to this. One of the milestones in the war was the Battle of Stalingrad, as the first major official defeat of Germany. Also technical accomplishments in telecommunications by the Allies enabled the detection of encrypted messages of the axle force, and thus came up with important information. Also, the key role in gaining advantage was contributed by America's involvement in the war, which had a lot of producer and human resources, soldiers ready to enter the war. Namely, America was able to launch a comprehensive arms production quite quickly, and achieved a large amount of weapons used by all allies throughout the war.
The answer is: D)
